package cn.org.timespace.easyframe.util;

import java.util.Calendar;
import java.util.Random;

public class StringUtil 
{

	public static boolean isNull(String str)
	{
		return str == null || str.trim().length() == 0;
	}
	
	public static boolean notNull(String str)
	{
		return !isNull(str);
	}
	
	public static boolean notNull(Object str)
	{
		if(str == null) return false;
		else return notNull(str.toString());
	}
	
	/**是否为空<p>
	 * 如果值=flag也认为是空
	 * @author William
	 * @param str
	 * @param flag
	 * @return
	 */
	public static boolean notNull(Object str,String flag)
	{
		if(str == null|| str.toString().trim().length() == 0) return false;
		else if(str.toString().trim().equals(flag)) return false;
		else return true;
		
		
	}
	
	public static String cut(String str,int len)
	{
		int le = str.length();
		return le > len ? str.substring(0,len) : str;
	}
	
	/**
	 * 根据当前时间生产随机数
	 * @return
	 */
	public static String generateRandom() {
		String randomValue = "";
		Random rand = new Random();// 生成随机数
		int random = rand.nextInt();

		Calendar calCurrent = Calendar.getInstance();
		int intDay = calCurrent.get(Calendar.DATE);
		int intMonth = calCurrent.get(Calendar.MONTH) + 1;
		int intYear = calCurrent.get(Calendar.YEAR);
		int intHour = calCurrent.get(Calendar.HOUR_OF_DAY);
		int intMin = calCurrent.get(Calendar.MINUTE);
		int intSecond = calCurrent.get(Calendar.SECOND);
		String now = String.valueOf(intYear) + String.valueOf(intMonth)
				+ String.valueOf(intDay) + String.valueOf(intHour) + String.valueOf(intMin) + String.valueOf(intSecond);

		randomValue = String.valueOf(random > 0 ? random : (-1) * random);
		if(randomValue.length() > 6)
			randomValue = randomValue.substring(0, 6);
		randomValue = now + randomValue;
		return randomValue;
	}
}
